On the Ability of the IEEE 802.11p and STDMA to Provide Predictable Channel Access

Executive Summary

Emerging traffic safety applications requiring low delay communications will need vehicle ad-hoc networks. The only communication standard currently supporting this is IEEE 802.11p. However, 802.11p uses the medium access method CSMA/CA, which has a major drawback: unbounded worst case channel access delay. The authors therefore propose an algorithm already in commercial use in the shipping industry: STDMA. With STDMA, nodes always get predictable channel access regardless of the number of competing nodes and the maximum delay is deterministic. In this paper, they elaborated with different parameter settings for the two protocols with the aim of improving performance without altering the standards.